1. Field of the Invention
The invention relates to radar systems generally, and more particularly to radar equipments which transmit pseudo-random binary coded continuous-wave signals and which have electronic means for angle determination associated therewith.
2. Description of the Prior Art
In the prior art the so-called pseudo-random-coded radar concept is, of itself, well known. The text "Modern Radar"--Analysis, Evaluation and System Design, by Random S. Berkowitz, published by John Wiley and Sons, Inc., New York, London and Sydney, (3rd Printing, August 1967, Library of Congress Catalog No. 65-21446, is one of many references describing this technique commonly known as PRC radar. Chapter 4 of the aforementioned text, entitled "Pseudo-random Binary Coded Waveforms," is particularly pertinent as an elementary reference in respect to PRC radar systems and concepts. The advantages in respect to high average power-on-target, favorable signal-to-noise ratio, and accuracy of range determination, as well as adaptability to Doppler velocity determination have long been well understood in this art.
The synergistic combination of the present invention also borrows from the so-called Doppler scanning radar technique, also known per se, in certain prior art forms. The structural aspects of such simulated Doppler systems are of interest as background, although the present invention is a new arrangement and combination of the commutated array technique combined with pseudo-random coding of the carrier.
The so-called Doppler scanning guidance system has been extensively described in the patent literature and other technical literature. For example, U.S. Pat. Nos. 3,626,419; 3,670,337; 3,728,729; and 3,754,261 are typical of the patent literature relating to this "simulated" Doppler technology. Also, the technical publication "Electrical Communication," published quarterly by International Telephone and Telegraph Corporation, contains a basic and quite complete description of that particular prior art as applied to Doppler navigation beacons in Volume 46, No. 4 (1971) beginning at Page 253.
Still further, U.S. patent application Ser. No. 634,890 filed Nov. 24, 1975, now U.S. Pat. No. 4,042,925 entitled Pseudo-Random Code (PRC) Surveillance Radar, describes an advanced PRC radar system in which the inherent range and Doppler determination ambiguities in PRC radar systems are dealt with to produce an optimum system in which the first range ambiguity was extended well beyond the useful range of the system, and in which Doppler ambiguities (i.e., target velocity multiples providing essentially the same Doppler response) are also placed beyond the velocity range of interest. That technology may be considered directly applicable to the present invention. The theory described in the aforementioned patent application Ser. No. 634,890, which is assigned to the assignee of the present application, is also helpful in appreciating the advantages to be obtained from the particular combination of the present invention.